Questions about creating interfaces for Multiple Regions
 

Hello,

I have a problem in creating two interfaces for three regions which is shown in attached picture 1. Box B and C are adjacent to A. I treated them as three parts and so three regions. Water flows from A to B and C respectively.

Obviously I need two interfaces here. I've tried several ways to do that but haven't succeeded. Here are those methods I've tried:

Method 1. Separating faces by patch, I can have three faces used as three boundaries, let's say, Boundary (face) A, B, C corresponding to Part A, B, C. Then I selected A and B to create a interface 1, and later A and C for interface 2. The type is internal interface.

No problem for the surface mesh, but when I checked the representation node, the Boundary for Box B and C were grey but interfaces were in color as shown in Picture 2 (In the picture, Box=A, Coolant=B, Gap=C). I used A as mastery face and B, C as slave. There were no faces for boundary B and C and there were several faces for interface 1 and 2 and also boundary A.

I tried to run the simulation and I couldn't run it. I'm guessing that the interface was not created successfully. Is that because I used Boundary A twice to create two interfaces?

Method 2. Okay, then I switched to another method, imprinting. I did locate part A and B, or Part A and C, but no part could be merged and this is the only information I got, no errors. Conformal match and tolerance is 0.1mm.

Method 3. This may be not correct. I selected Boundary A, B, C at the same time to create ONE interface and also got grey interface.

So any one knows what I can do to deal with such a geometry? Thanks a lot!

Are you using the parts tab or just regions and boundaries? If you are using parts, then it sounds like you may have some boundaries that are not associated with any part surfaces.

The whole "parts" system in Star-CCM+ is asinine by the way. I can see how you could get confused.

Thanks for your reply. I imported them as three parts and assigned them as 3 regions.

I created these three parts separately and assembled them together in Solidwors. The coordinates for these three parts are different but I check the model carefully and I'm sure there is no gap on the interface. However, although these three parts are fully connected, the coordinates for the adjacent points are different. For example, point A belonged to Part A is (1,0,0) while Point B belonged to part B is (1,1,1) although they are physically at the same Z level and should have the same Z. But when I measure the normal distance between Point A and B in Z direction, the distance reported is zero.

I measured these two points in Starccm, the coordinate were unified I think. So I'm not sure if this is the reason.

Please note that Box A, B, C are just simplified model. The difference between the real and the simplified is Part B is made of 18 cylindrical pipes and so the interface is just 18 circles. Interface for Part A is like a cross shape "+".

Thanks!

Sorry i didnt see that you where looking at the regions level. So my first posting was wrong. Dont notice the picture.

Try to delete all references to the parts level for the regions. You can do this at the properties window for each region. Then start the meshing pipeline. Maybe this helps.

Method 1 should work fine. You can use a boundary several times to create an interface, that doesn't cause an issue.
Also it's good when you don't have any faces on the boundary but all on the interface. That means, you will get a conformal match which is good for the results.

What error message did you get? What exactly happens when you try to run the simulation?

Hey Abdul,

Thanks for your reply. The issue had been solved after I contacted some staff in the Star CD. The way used was to imprint those related parts so that the faces used to create interfaces could be generated.

I did have issues when I used one boundary face twice to create an interface. The first error was there was no face at all on the interface. Also, the flow couldn't flow through the interface, which meant that the interface wasn't created properly.

Anyway, thanks again for your continuous help.

famerfamer

Hi

I have got the same problem when I wanted to simulate a hip with a propeller, literally, a self-propulsion ship. Although I set up everything so clear in geometry part, I come across disjoint error at the time of meshing while it stated: "Region constructed contains 1836 faces from region Body 4 and 446532 faces from region domain".

It would be appreciated if somebody helps me with this issue.

Regards,
Hamed

You should create a new thread rather than dig up one from almost 8 years ago.

That being said...

One thing I always try to do with multi region models, prior to importing from CAD, is to clone the conformal faces where regions meet. What I mean by this is to copy the face from region A, delete the mating face from region B, then use the copied face from region A to sew up region B into a new solid/region.

Obviously, how you generate the import geometry matters. I run solid works and this works well for me. I rarely have any issues with interfaces when I do this.